While many animal species are also facing extinction, we share almost 99% of our DNA with chimpanzees. The possibility of losing our closest genetic relative has some researchers alarmed.

The reasons behind the chimps' decline are varied and complicated. In the wild, habitat destruction caused by logging and slash-and-burn agriculture; fatal diseases like Ebola; and the illegal hunting and poaching of these animals for food, pets, and medicinal purposes are drastically reducing their numbers. Civil war and political instability in the Congo Basin, the region in Africa where most Bonobo chimps live, are also contributing to the rapid demise of these animals.

According to the University of Michigan Museum of Zoology, chimpanzees reproduce once every three to six years , and generally have single offspring, rather than twins or litters. These low rates of reproduction combined with human encroachment on habitat, means that chimps are unable to replace themselves in the wild quickly enough to ensure their survival.

Although chimpanzees live and reproduce in zoos and research centers throughout the world, life in captivity does not necessarily equal survival as a species. "There's more to being a chimpanzee than having chimpanzee genes," argues Dr. Jim Moore, associate professor of Anthropology at UC San Diego. And now even those captive populations are in decline.

In the 1980's when researchers saw great promise in working with chimps to develop a vaccine for HIV/AIDS, there was a huge spike in chimp breeding with these goals in mind. What the research showed, however, was unexpected-chimps are naturally resistant to developing AIDS from the HIV virus. When this resistance became apparent, vaccine researchers no longer saw the value in continuing their work with chimps. And, in fact, many animal rights advocates, like the Humane Society, have long argued that not only is medical testing on chimps cruel, it doesn't yield useful results.

But it is the differences between us, not just the similarities, which intrigue some researchers. The human genome was mapped in 2001. And in 2005, the chimp genome followed. Since chimps are not as seriously affected by many of the major diseases now stumping medical science-diseases like Alzheimer's and HIV/AIDS—some researchers, such as Dr. Ajit Varki of UC San Diego, believe that a greater understanding of how chimp DNA enables this resistance can shed light on the development of treatment and prevention strategies for these illnesses that are so threatening to human beings "It is ironic," says Dr. Varki, "That great apes face extinction just when we sequenced the chimp genome."

These are complicated questions, to be sure. So, what can be done to save the chimps and, in turn, possibly help us to better understand both ourselves and our relationship to other species? We've included some links to just a few of the organizations working on this issue.

Daniel Povinelli reviews some of the most provocative experimental results to have emerged from comparative labs in the past few years, exploring nonhuman animals' understanding of causal-logical relations. (Thanks to Annual Reviews for granting complimentary access to The DNA Files users.)